Nested translation is a hardware feature that is supported by many modern IOMMU hardwares. It has two stages (stage-1, stage-2) address translation to get access to the physical address. stage-1 translation table is owned by userspace (e.g. by a guest OS), while stage-2 is owned by kernel. Changes to stage-1 translation table should be followed by an IOTLB invalidation.
Take Intel VT-d as an example, the stage-1 translation table is I/O page table. As the below diagram shows, guest I/O page table pointer in GPA (guest physical address) is passed to host and be used to perform the stage-1 address translation. Along with it, modifications to present mappings in the guest I/O page table should be followed with an IOTLB invalidation.
.-------------. .---------------------------. | vIOMMU | | Guest I/O page table | | | '---------------------------' .----------------/ | PASID Entry |--- PASID cache flush --+ '-------------' | | | V | | I/O page table pointer in GPA '-------------' Guest ------| Shadow |---------------------------|-------- v v v Host .-------------. .------------------------. | pIOMMU | | FS for GIOVA->GPA | | | '------------------------' .----------------/ | | PASID Entry | V (Nested xlate) '----------------.----------------------------------. | | | SS for GPA->HPA, unmanaged domain| | | '----------------------------------' '-------------' Where: - FS = First stage page tables - SS = Second stage page tables <Intel VT-d Nested translation>
In IOMMUFD, all the translation tables are tracked by hw_pagetable (hwpt) and each has an iommu_domain allocated from iommu driver. So in this series hw_pagetable and iommu_domain means the same thing if no special note. IOMMUFD has already supported allocating hw_pagetable that is linked with an IOAS. However, nesting requires IOMMUFD to allow allocating hw_pagetable with driver specific parameters and interface to sync stage-1 IOTLB as user owns the stage-1 translation table.
This series is based on the iommu hw info reporting series [1]. It first introduces new iommu op for allocating domains with user data and the op for invalidate stage-1 IOTLB, and then extend the IOMMUFD internal infrastructure to accept user_data and parent hwpt, then relay the data to iommu core to allocate user iommu_domain. After it, extends the ioctl IOMMU_HWPT_ALLOC to accept user data and stage-2 hwpt ID to allocate hwpt. Along with it, ioctl IOMMU_HWPT_INVALIDATE is added to invalidate stage-1 IOTLB. This is needed for user-managed hwpts. Selftest is added as well to cover the new ioctls.
Complete code can be found in [2], QEMU could can be found in [3].
At last, this is a team work together with Nicolin Chen, Lu Baolu. Thanks them for the help. ^_^. Look forward to your feedbacks.
[1] https://lore.kernel.org/linux-iommu/20230724105936.107042-1-yi.l.liu@intel.c... [2] https://github.com/yiliu1765/iommufd/tree/iommufd_nesting [3] https://github.com/yiliu1765/qemu/tree/wip/iommufd_rfcv4_nesting
Change log:
v3: - Add new uAPI things in alphabetical order - Pass in "enum iommu_hwpt_type hwpt_type" to op->domain_alloc_user for sanity, replacing the previous op->domain_alloc_user_data_len solution - Return ERR_PTR from domain_alloc_user instead of NULL - Only add IOMMU_RESV_SW_MSI to kernel-managed HWPT in nested translation (Kevin) - Add IOMMU_RESV_IOVA_RANGES to report resv iova ranges to userspace hence userspace is able to exclude the ranges in the stage-1 HWPT (e.g. guest I/O page table). (Kevin) - Add selftest coverage for the new IOMMU_RESV_IOVA_RANGES ioctl - Minor changes per Kevin's inputs
v2: https://lore.kernel.org/linux-iommu/20230511143844.22693-1-yi.l.liu@intel.co... - Add union iommu_domain_user_data to include all user data structures to avoid passing void * in kernel APIs. - Add iommu op to return user data length for user domain allocation - Rename struct iommu_hwpt_alloc::data_type to be hwpt_type - Store the invalidation data length in iommu_domain_ops::cache_invalidate_user_data_len - Convert cache_invalidate_user op to be int instead of void - Remove @data_type in struct iommu_hwpt_invalidate - Remove out_hwpt_type_bitmap in struct iommu_hw_info hence drop patch 08 of v1
v1: https://lore.kernel.org/linux-iommu/20230309080910.607396-1-yi.l.liu@intel.c...
Thanks, Yi Liu
Lu Baolu (2): iommu: Add new iommu op to create domains owned by userspace iommu: Add nested domain support
Nicolin Chen (6): iommufd/hw_pagetable: Do not populate user-managed hw_pagetables iommufd: Only enforce IOMMU_RESV_SW_MSI when attaching user-managed HWPT iommufd/selftest: Add domain_alloc_user() support in iommu mock iommufd/selftest: Add coverage for IOMMU_HWPT_ALLOC with user data iommufd/selftest: Add IOMMU_TEST_OP_MD_CHECK_IOTLB test op iommufd/selftest: Add coverage for IOMMU_HWPT_INVALIDATE ioctl
Yi Liu (9): iommufd/hw_pagetable: Use domain_alloc_user op for domain allocation iommufd: Pass in hwpt_type/parent/user_data to iommufd_hw_pagetable_alloc() iommufd: Add IOMMU_RESV_IOVA_RANGES iommufd: IOMMU_HWPT_ALLOC allocation with user data iommufd: Add IOMMU_HWPT_INVALIDATE iommufd/selftest: Add a helper to get test device iommufd/selftest: Add IOMMU_TEST_OP_DEV_[ADD|DEL]_RESERVED to add/del reserved regions to selftest device iommufd/selftest: Add .get_resv_regions() for mock_dev iommufd/selftest: Add coverage for IOMMU_RESV_IOVA_RANGES
drivers/iommu/iommufd/device.c | 9 +- drivers/iommu/iommufd/hw_pagetable.c | 181 +++++++++++- drivers/iommu/iommufd/io_pagetable.c | 5 +- drivers/iommu/iommufd/iommufd_private.h | 20 +- drivers/iommu/iommufd/iommufd_test.h | 36 +++ drivers/iommu/iommufd/main.c | 59 +++- drivers/iommu/iommufd/selftest.c | 266 ++++++++++++++++-- include/linux/iommu.h | 34 +++ include/uapi/linux/iommufd.h | 96 ++++++- tools/testing/selftests/iommu/iommufd.c | 224 ++++++++++++++- tools/testing/selftests/iommu/iommufd_utils.h | 70 +++++ 11 files changed, 958 insertions(+), 42 deletions(-)